1. Field of the Invention
The present invention relates to an inkjet recording apparatus.
2. Related Art
Conventionally, inkjet recording apparatus that record images, characters, and so forth by jetting a liquid such as ink onto a liquid-absorbing recording medium surface have had the problem that they end up causing damage to the printed materials on which they have finished processing because of a phenomenon called blocking where a liquid such as the ink that forms the image, a solvent, or a dispersion medium seeps into the recording medium and the inks on the printed materials that have been accumulated stick (fix) to each other because of insufficient drying and insufficient fixing of the image portions. Particularly in high-productivity inkjet presses, there is a tendency for the drying and fixing time to become shorter, so it becomes easier for insufficient drying and insufficient fixing to arise and it also becomes easier for blocking to occur in cases where printing has been performed on thick paper.
However, performing long drying across the board on the entire recording medium in a drying unit is not desirable because it lowers the processing capacity of the apparatus because it increases the processing time of the entire process. Further, preparing a dryer of a size that covers the entire width of the recording medium is inefficient in a case where there are plural types and sizes of recording media, and in the paper width neighborhoods there is the concern that paper uplift will occur because the drying air goes around to the reverse side of the medium.
For this reason, as shown in FIG. 8, there has been disclosed an image recording apparatus that is equipped with a drying unit 242 movable in a conveyance width direction on a conveyance direction downstream side of an inkjet recording head and blows drying air on both sides in the conveyance width direction (e.g., see Japanese Patent Publication Laid-Open No. 2010-125834).
Here, the moisture content (quantity of absorbed liquid) of the recording medium differs between the image portion of the recording medium—that is, the portion onto which the ink has been jetted and which has absorbed the ink—and the non-image portion—that is, the white background portion that has not absorbed the ink. Thus, there is the problem that if the recording medium is strongly dried across the board, this causes non-uniform contraction of the recording medium and produces deformation (cockling) in the recording medium after processing, but the configuration described in Japanese Patent Publication Laid-Open No. 2010-125834 has the problem that it cannot deal with this difference in moisture content between the white background portion and the image portion.
That is, when the drying unit 242 of the configuration described in Japanese Patent Publication Laid-Open No. 2010-125834 (FIG. 8) blows drying air (drying energy) across the board onto the paper, there is the concern that the white background portion whose moisture content is low will be over-dried and that the paper will cockle. What is needed is drying control based on changes in print modes in which the output image to be recorded on the recording medium and the conveyance speed (single paper feed amount) change.